Edward Snowden, the former intelligence contractor who leaked thousands of highly classified documents which revealed the scale of US and British surveillance, has made an 11th hour pitch to Barack Obama to grant him a presidential pardon before leaving office.

Snowden, whose disclosures included the revelation that the US National Security Agency was collecting "metadata" on Americans' phone calls, is living in exile in Moscow, and would face up to 30 years in prison for alleged violations of the Espionage Act if he returned to the US.

Calling the leaks "vital" and beneficial, Mr Snowden said that even if he was legally guilty, he had not done anything morally wrong.

Barack Obama speaks with Vladimir Putin at the G-20 summit in China. The White House has urged Snowden to return from Russia to face chargesCredit:
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“Yes, there are laws on the books that say one thing, but that is perhaps why the pardon power exists – for the exceptions, for the things that may seem unlawful in letters on a page but when we look at them morally, when we look at them ethically, when we look at the results, it seems these were necessary things, these were vital things,” he told the Guardian.

“If not for these disclosures, if not for these revelations, we would be worse off,” he added.

The White House says Mr Obama still believes Mr Snowden must face the charges against him in court.

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"Mr Snowden has been charged with serious crimes, and it’s the policy of the administration that Mr Snowden should return to the United States and face those charges," Josh Earnest, the White House press secretary said on Monday. "That's what the president believes."

Mr Holder, a close confidante of Mr Obama's, said Mr Snowden had acted illegally, but had raised a much needed debate over surveillance that had led to reforms.

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He did not agree that Snowden should be pardoned, however.

"Go to trial, try to cut a deal. I think there has to be a consequence for what he has done," he said. "But I think ... a judge could take into account the usefulness of having had that national debate."